Transcript for Caught on Tape: Rare Animals Lead Secret Lives After Dark

And finally, tonight, the discovery channel will look at the secret lives of mysterious and rare animals, particularly one species, the black rhino, thought to be one of the most solitary creatures on earth. But a special new camera is about to reveal what we never knew was happening by the light of the moon. Abc's sharyn alfonsi has a sneak peek. Reporter: It is a peek into a secret world we've never seen. Giraffes, in a knockout battle for domination. And then, the black rhino, a notoriously solitary animal. Or so we thought. Watch as rhinos secretly gather at a waterhole at night. A mother emerging with her calf. Their vision is poor, but their sense of smell is sharp. They greet each other with surprising gentleness. Nobody knew about it because you can't see it. Reporter: Mike gunton produced the new africa series for discovery. He says there have been legends of such secret gatherings, but few have witnessed it and no one until now has ever been able to film it. The only way you could do it is by using a special camera which we developed to see just under the star light. Very but there was more. Microphones hidden under rocks revealed a secret language of black rhinos, too. No one knows for sure, but it's believed this is a friendly sound. And overture from the normally cagey rhino. Animals that have been around for millions of years, still able to surprise us. Sharyn alfonsi, abc news, new york.

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